说明：   针对三相桥式整流电路的谐波和无功功率的特点，提出几种滤波方案，并进行比较，最终确定了用有源滤波方案。对于有源滤波器，本论文从结构上比较后选用并联电压型有源滤波器。
(The thesis introduces several kind of filter schemes, which is aimed at the harmonic characteristic of three-phase bridge rectifier circuit .After comparison,the thesis chooses the active filter scheme,in view of the active filter, after the comparesion of structure,finally, the thesis chooses the parallel-voltage active filter.)